1. Field of the Invention
The present application relates to devices and methods involving a spinal implant for placement in a disc space of a spine. For example, in some embodiments, the present application relates to devices and methods involving a nucleus replacement device for placement in a disc space of a spine. In some embodiments, the present application relates to devices and methods involving an intervertebral cage device for placement in a disc space of a spine.
2. Description of the Related Art
The spine relies on intervertebral spinal discs in between adjacent vertebrae to serve as mechanical cushions and transmit compressive loads. Spinal discs are composed of an outer annulus fibrosus that surrounds an inner nucleus pulposus. The annulus fibrosus is composed of laminae of fibrous tissue and fibrocartilage, while the nucleus pulposus is composed of water, chondrocytes, collagen fibrils and proteoglycan aggrecans that have hyaluronic long chains. The nucleus pulposus functions to distribute hydraulic pressure in all directions within each disc under compressive loads.
The nucleus pulposus, which begins early in life as eighty percent water, slowly desiccates with age. This causes the spinal disc to lose its cushioning ability and ability to bear loads, resulting in pain in the back and lower extremities. To resolve these problems, the degenerated nucleus may be removed and replaced. In some other cases, the nucleus may be removed and the vertebrae may be fused together in a spinal fusion procedure, which may include implanting an intervertebral cage and/or bone growth material to facilitate fusion of the vertebrae.